1. Field of the Invention
The present invention relates to electronically eliminating or inhibiting the presence and reproduction of biological contaminants within fluid fuels or lubricants, tanks, or piping systems.
2. Description of Related Art
It has been known since the late 1800's that biological contaminants exist in hydrocarbon fuels. For instance, fungi and microbes (e.g., bacterium) were found to have been living and reproducing on purely hydrocarbon diets. Various other types of biological contaminants have also been reported in petroleum products, fuels and fuel systems over the years.
Biological contaminants are undesirable within flowing fluids, especially liquid fuels and lubricants, due to their tendency to grow and aggregate into clumps that form slime or a film, often referred to as a biofilm or a biomass. Both biological slime and biofilms generally grow at the bottoms of storage and piping systems, and include multiple species of contaminants that cooperate together in destructive ways by casting off filaments and/or tendrils that coat the sensors and filters within the filter tanks. Larger pieces of debris from these agglomerated biological contaminants can break off over time to abruptly decrease or even stop system performance.
It has also been shown that microbes within the biological contaminants can lead to microbial induced corrosion at the containment wall. This type of corrosion is created as an electrical phenomenon in combination with several processing conditions that cause microbes to separate metal components from the liquid. These separated metal components accumulate as acid byproducts including, for example, hydrochloric, nitric, nitrous or sulfuric acids, all of which deteriorate the fluid system.
Several approaches have been developed in order to avoid liquid fuel or lubricant system corrosion and deterioration. These approaches include chemical treatments as well as physical treatments and/or approaches. Chemical techniques for killing microbes involve the use of specially manufactured chemical micro-biocides that poison the biological cells known to affect and deteriorate fuels and lubricants. Many of these micro-biocides are controlled and government regulated due to their toxicity and difficulty of disposal. Often, when chemical biocides are used to eliminate microbes in liquids, the waste generated by the filtered liquid is toxic and must be carefully removed and disposed of so as not to contaminate the environment. For instance, ethylene glycol monomethyl ether (EGME), was commonly used as both a micro-biocide and a deicing agent for aircraft, however, its use has ceased due to its environmental toxicity. As such, many chemical treatments are slowly falling out of use due to their toxicity.
Physical treatments for killing microbes in liquids are typically broken into two primary categories, cell removal and cell disruption. Filtration is the most common cell or microbe removal technology. Other known cell disruption technologies include electrochemical, ultrasound, microwave, germicidal ultraviolet light (UV) and magnetic fields.
Electrochemical approaches are used in aqueous (i.e., water-based) liquid flows where current is conducted directly through the water to form short-lived chemistries in the zone of conduction that kill the bacteria. However, in highly nonconductive fuels and lubricants, electrochemical approaches are inefficient and often not viable. Ultrasonic techniques have also been implemented to disinfect aqueous media (e.g., drinking water). Yet, these techniques often require 60 minutes, or more, to achieve a kill rate of over 90%.
Microwave techniques enable the absorption of the microwaves into the aqueous molecular structures, and as such, are often used for sterilization of liquid food products. The relatively low energies used in microwave techniques may oxidize any alkynes present in fuels or lubricants. As such, the tendency for alkynes to oxidize at relatively low energies and damage the fuel by oxidation results in these approaches to be economically undesirable for fuels and/or lubricants.
Germicidal UV implement short wavelength ultraviolet radiation to destroy bacteria, molds and other bacterial organism for water treatment, typically in heating, ventilation and air-conditioning applications. In doing so, UV lamps at 185 nm and 254 nm light produce ozone with the 185 nm wavelengths and hydroxide radicals on instruction of the ozone with the 254 nm wavelength. However, these low powered ultraviolet sources are not sufficient for destroying bacteria, molds and other bacterial organisms in fuels and lubricants. Because most of the UV Energy was adsorbed by the first 10 um of fuel.
Magnetic field techniques use strong permanent magnets to damage cells as they pass by these fields at moderate flow rates. The magnetic fields cause any contaminants within the liquid to move back and forth until this movement causes the contaminant to break apart or split. The magnetic fields are passive fields that only break or split the contaminants into pieces, and do not further treat such contaminants thereafter. The split and/or broken pieces of contaminants continue to maintain their genetic make-up intact and unchanged, such that, these fragments or pieces are capable of growing, reproducing and even taking on genetic material or code from other contaminants. As such, any contaminant or fragment thereof having been passed through a magnetic field remains to be capable of growing into a biofilm or biomass. Magnets depend on fluids passing extremely close to concentrated field lines, at high velocity to create a large enough coupling, to influence the microbe. Most magnetic systems utilize open channels to limit the differential pressure across the device, rendering them less effective.
Therefore, a need continues to exist for improved non-chemical micro-inhibitors for systems, apparatus and methods that eliminate and destroy biological contaminants and microbes within liquid fuels and/or lubricants, and render any remaining biological contaminants within the treated effluent unviable.